A method of this type and a corresponding needle bar are known from DE 37 22 481 B1. Herein it is already described that is possible to work with overpressure or underpressure for producing a cleaning air-flow. The measures described in the generic patent specification aim exclusively to replace the previously mechanically executed cleaning of the cleaning comb, e.g. by means of cleaning blades, as they are approximately known from DE 29 42 588 A1, by a cleaning by means of an airflow, which mechanically treats the needles with care, and which is also feasible in case of narrow spacial conditions.